AutoSPInstaller should work without AD. You'll still need to setup your accounts ahead of time and remember to use the same naming format. So, instead of "DOMAIN\service_account" use "SERVERNAME\service_account"

Actually the ValidateCredentials function will throw an error if it detects a non-domain account being used for install. I suppose you could comment that out, but the idea was for the script to check for supported scenarios and exit otherwise.